The objectives of maximizing snow skier safety must be balanced with the requirements of keeping the skier attached to his or her skis in varying conditions. These objectives have received a great deal of engineering and commercial attention over the past thirty years but increasing skier safety remains an objective.
When the skier to release from his or her skis during falls may result in bone fractures, particularly to the legs, while unexpected release during controlled skiing can be equally injurious. A system to safely release the skier must not only reliably release under specified forces and directions, but must also, to be commercially practical, be adjustable to account for skier ability, equipment variations and environmental conditions. Further, the system must be durable and reliably operable over a wide range of temperature and moisture conditions.
Skiers can experience different types of leg injury causing falls during skiing. One type of injury results from rapid deceleration when skis strike an object directly ahead of the skier. The object could be quite small, allowing the skier to easily travel over it, if released from the immobilized skis. Unless the boot is cushioned and immediately released allowing the heel to rotate upward as well as releasing the toe, substantial leg injury can result in an otherwise non-injury accident. A second type of injury is a lateral twisting which can occur when the long edge of a ski catches, that is, fails to track during turns. Unless the boot is cushioned and immediately released allowing the toe and heel to rotate in the plane of the ground surface, serious leg injury can result in an otherwise non-injury accident. In divergent and other types of falls, the skis may get caught in deep snow or other obstructions where a ski is not parallel to the ground surface. The skier may also fall in different directions during turns or other maneuvers. Release of the ski boot must allow rotation and release in planes other than those parallel and perpendicular to the ground surface in order to avoid leg injury. At the same time, ski bindings must also not prematurely release the skis during controlled, but severe, maneuvers which exert different forces, but in similar directions to those where immediate release is required.
Existing ski equipment is increasingly more complex structurally to particularly address the considerations of specific release angles and adjustability. An example of such complexity is Swiss patent No. 571,838 to Besson. Besson discloses a sole plate, sole plate attachment to ski boots, two contoured face plates, a face plate mounting block, plungers, and related adjusting mechanisms and ski attachment hardware to realise the direction specific force release features. U.S. Pat. No. 3,781,028 to Gertsch et al. and U.S. Pat. No. 3,902,729 to Druss disclose multiple plungers/release points to realize different release forces in different directions. Such increased complexity, however, also increases the potential for lower reliability due to water/ice intrusion into these mechanisms, changing operational characteristics or even rendering the ski equipment wholly inoperable.
A second design approach compromises safety to gain operational advantages. For example, in order to permit step-in access to the ski binding, the heel attachment of commercial bindings is designed to be less adaptable to the required range and directions of release angles and more attention has been given to the range of release angles of the toepiece. Such bindings may not release in response to a rotational force emanating from the heel the toe. Similarly, some bindings do not release in straight-forward falls and angled upward falls because the release directions of the binding have not been continuous. Rather, they are oriented in specific directions and constraint by the moving parts of the system. Almost all bindings are designed to easily release (in a horizontal plane 90.degree. from vertical) by such mechanisms as horizontally swiveling toepieces, but those bindings will not as easily or reliably release at a release force angle of, say, 25.degree. unless a separate rotational mechanism is incorporated in the toepiece to move through that angle. In other words, few bindings can operate over the entire 180.degree. range of release angles, both from toe and heel restraining points. No known binding enables continuous or periodic adjustment of the release forces throughout this range.
What is needed is a ski binding system that can be configured to release at any predetermined unidirectional force or release angle over a continuous range of forces and angles. The present invention achieves this objective and overcomes the above-described shortcomings of the prior art.
A further objective of the within invention is to provide a ski binding system that will release in response to rotational forces that do not trigger a release within existing systems.
Another objective of the within invention is to accommodate to the continuous range of release specifications while reliably retaining the skier in the binding in all conditions except during falls.
Further objective of the within invention is to provide a greatly simplified ski binding system with a minimum of moving parts in order that reliability and watertight integrity can be maximized.
Another objective of the within invention is to provide a ski binding system that can be easily adjusted or modified to accommodate the specific release requirements of individual skiers of all abilities.
Another objective of the within invention is to provide a ski binding system that can withstand and absorb normal shocks and transient loadings without release and also cushion the transmission of these loadings to the skier.
Finally, it is an objective of the within invention to provide a system that will not be limited to discrete or separated operating angles of release, but provide continuous release capability over the entire range of angles and forces which a ski binding system addresses.
The within invention claims particularly a plunger and socket or receiving groove attachment mechanism with a precisely machined socket or groove contoured to enable release of the plunger mechanism at specified forces and angles. The closest reference in the art known to the applicant is Gertsch U.S. Pat. No. 3,781,028, Safety Ski Binding. Gertsch is limited however, in several ways that the within device is not; specifically Gertsch uses a socket providing for equal release forces at all angles of incidence between retaining pin and boot. Further this device specifies a separate metal plate to hold the socket which plate then must be externally attached to the boot, and a four-point locking pin system is specified or two points on either end of the boot. By contrast the within invention uses either a socket or groove selectively shaped and contoured in a non-uniform fashion so as to provide unequal release forces at different angles of incidence of pin to boot, and provides that the socket or groove may be integral with the boot sole, a preferred configuration as it decreases by 1 degree the freedom of motion between the skier and the ski. Also the within invention can be configured to operate with any number of retaining pins that might be desired to tailor the response to release forces although a 3 point fixation system is considered to be the preferred embodiment because fewer may permit unstable roll moments while more may inhibit free boot movement out of the binding during forward twisting falls. Other similarly limited systems in the art include Ramillon U.S. Pat. No. 3,936,065 and Salo, on U.S. Pat. No. 4,003,587, both of which require more moving parts and are limited in responsiveness and adjustability. Further, the use of the groove permits shock absorption action of the boot on the binding which the socket mode does not permit. This shock absorption action cushions and prevents injury to the skier, as well as allows bindings to absorb normal loadings without release.
Besson (Switzerland Patent No. 574,838) shows a ski binding system which allows specific release forces in several different directions, however, combinations of forces or forces out of the specific directions provided for are not addressed. More importantly, a disadvantangeous mechanical complexity of multiple components is required. Further disadvantages from this complexity and multiplicity occur from a doubling of releasable attachment equipment (a first attachment of ski boot to boot plate and a second attachment of boot plate to ski occurs). Additionally, the location of the contoured plates does not allow variations in skier heel-to-toe loadings. Moreover, this plate forces a fixed relationship between release forces at the heel and toe. Finally, the ability to walk on the boot plate is limited.